unknown

From un- +‎ known, past participle of know. Compare Old English ungecnawen.

• (UK) IPA^(key): /ʌnˈnəʊn/
• (US) enPR: ŭn-nōnʹ, IPA^(key): /ʌnˈnoʊn/

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unknown (comparative more unknown, superlative most unknown)

1. (sometimes postpositive) Not known; unidentified; not well known.
   • 1898, Winston Churchill, chapter 4, in The Celebrity:

     The Celebrity, by arts unknown, induced Mrs. Judge Short and two other ladies to call at Mohair on an afternoon when Mr. Cooke was trying a trotter on the track. The three returned wondering and charmed with Mrs. Cooke; they were sure she had had no hand in the furnishing of that atrocious house.

• well-known
• famous
• known

• unknown quantity

unknown (plural unknowns)

1. (algebra) A variable (usually x, y or z) whose value is to be found.
2. Any thing, place, or situation about which nothing is known; an unknown fact or piece of information.
   • 1957, Ethel Erford Hewitt, Into the Unknown: An Historical Novel, page 351:

     Had God walked close beside her into the unknown?

   • 2003 [2002], Donald Rumsfeld, Hart Seely, editor, Pieces of Intelligence: The Existential Poetry of Donald H. Rumsfeld:

     As we know, There are known knowns. There are things we know we know. We also know There are known unknowns. That is to say We know there are some things We do not know.

3. A person of no identity; a nonentity
   • 1965, Bob Dylan, Like a Rolling Stone

     How does it feel

     To be on your own

     With no direction home

     Like a complete unknown

     Like a rolling stone?